In a manufacturing line of microdevices such as semiconductor devices, overlay exposure between a plurality of exposure apparatuses (apparatus numbers) is often performed. In such a case, since a grid error of a stage between exposure apparatuses (an error between stage coordinate systems that define a moving position of a wafer in the exposure apparatuses) exists, an overlay error is generated. In addition, even in the case of having no grid error of a stage between exposure apparatuses or in the case of using the same exposure apparatus, in the overlay between respective layers to which process processing steps such as etching, CVD (Chemical Vapor Deposition) or CMP (Chemical Mechanical Polishing) are performed, an overlay error may be generated at times because the process steps give distortion of an arrangement of shot areas.
In such a case, when an arrangement error variation of shot areas on a wafer that causes an overlay error (an arrangement error of shot areas) is a linear-component, the error can be removed by wafer alignment by the EGA method in which positional coordinates of only a plurality (three or more are required, and about 7 to 15 in general) of sample shot areas (also referred to as alignment shot areas) that are selected in advance on a wafer are measured, and from the measurement values, positional coordinates (an arrangement of shot areas) of all shot areas on the wafer is calculated using a statistical computation processing (the least-squares method and the like) (e.g. refer to Patent Document 1). However, when the arrangement error variation of shot areas is a non-linear component, it is difficult to remove it by the wafer alignment by the EGA method.
As a way to improve the above defects of the wafer alignment by the EGA method, recently a lithography system including an exposure apparatus has been proposed that can achieve exposure maintaining the overlay precision preferable even in the case when an arrangement error variation of shot areas in a wafer includes a non-linear component (e.g. refer to Patent Document 2).
However, in an exposure apparatus composing a lithography system disclosed in Patent Document 2, mainly aiming at correction of a grid error of a stage between exposure apparatuses, positional information of all shot areas of a wafer at the head of each lot has been measured in actual, then using the actual measurement values of positional information obtained by the measurement a linear component and a non-linear component of an arrangement deviation of shot areas on the wafer has been obtained, and the non-linear component has been stored as a correction value. With respect to the second and succeeding wafers in the same lot, using arrangement coordinates of all shot areas on the wafers obtained by performing the normal eight-point EGA and the non-linear component (the correction value) obtained for the wafer at the head of the lot, the wafers have been moved and overlay exposure has been performed to each shot area.
While an arrangement deviation of each shot area on the wafer hardly varies with respect to each lot, it is considered that how often and how the arrangement deviation varies depends on various factors such as an environment where the apparatus is placed, or an exposure process or its combination, and therefore, it is difficult to predict that.
Thus, as disclosed in Patent Document 2, when positional information of all shot areas on a wafer at the head of each lot is measured in actual, as a consequence it takes excessive time to measure the positional information of all shot areas, which decrease throughput more than it should be.
In addition, when taking into consideration one wafer, it is empirically known that how an arrangement deviation of shot areas varies depends on a place on the wafer. Therefore, it is hard to say that a method, in which positional information of all shot areas on a wafer at the head of the lot is measured in actual, is efficient.
Patent Document 1: the U.S. Pat. No. 4,780,617
Patent Document 2: the U.S. patent application Publication No. U.S. 2002/0042664